Background: The immune system plays a critical role in regulating amyloid-beta (Aβ) metabolism in Alzheimer's Disease (AD). Both T and B lymphocytes are involved in the pathogenesis of AD. The sphingosine-1-phosphate (S1P) receptor modulator fingolimod used in the treatment of multiple sclerosis, can promote lymphocyte homing, potentially reducing the infiltration of peripheral lymphocytes into the brain.

Methods: In this study, 8-month-old APP/PS1 mice were orally administered fingolimod at a dose of 1 mg/kg/day or saline as a control for 2 months. After treatment, the mice were subjected to behavioral tests, pathological examinations, and biochemical analyses to evaluate behavioral deficits and AD-type pathologies.

Results: Fingolimod inhibits the infiltration of peripheral lymphocytes into the brain and reduces neuroinflammation. Fingolimod enhances cognitive function and alleviates brain Aβ deposition. Additionally, fingolimod treatment mitigates other AD-related pathologies, including Tau hyperphosphorylation, neuroinflammation, and neurodegeneration. Proteomic analysis further confirms the therapeutic effects of fingolimod in AD, reflected by the downregulation of proteins involved in multiple AD-associated pathways.

Conclusions: This study illustrates that fingolimod effectively ameliorates multiple pathological features of AD, highlighting its potential as a promising therapeutic candidate for the disease.